R032

The Forgetful Tailor: Case Report of an Ectopic Mediastinal Parathyroid Adenoma

Preeshila Behary, Jenny Vaughan, Bareen Shah, Fausto Palazzo, Adil Al-Hahhas and Kevin Baynes

Ealing Hospital

Abstract:

Introduction:

Ectopic parathyroid adenoma is an uncommon cause of primary hyperparathyroidism.

Accurate preoperative localisation by radiological imaging is necessary.

We report a case in which a Tc-99m Sestamibi scan and a CT with contrast were used successfully to locate and surgically treat an ectopic mediastinal parathyroid adenoma.

Case Presentation:

A 53 year old gentleman was referred to the Endocrine clinic by the Neurology team after presenting to them with poor concentration and memory problems. He had a corrected Calcium of 3.30 mmol/L and Parathyroid hormone (PTH) of 33 pmol/L.

There was no known family history of parathyroid disease. His calcium/ creatinine excretion ratio was >0.02, making Familial Hypocalciuric Hypercalcaemia unlikely.

Ultrasound imaging of his neck showed no enlarged parathyroid glands and no lymphadenopathy.

A Tc-99m Sestamibi scan showed increased tracer uptake within a lesion situated inferior to the thyroid gland, in keeping with an ectopic parathyroid adenoma.

CT chest with contrast confirmed a nodular mass of 2115 mm in the upper anterior mediastinum.

Management and Outcome:

He was referred to the Surgical team and underwent neck exploration and parathyroidectomy. The procedure was uncomplicated and the left inferior parathyroid gland was easily found within the thymus in the anterior mediastinum.

Histology confirmed a parathyroid adenoma. Post operatively, his Calcium and PTH levels normalised and his concentration and memory problems resolved. He has now been discharged from the endocrine and surgical clinic.

Discussion:

About 10-20% of all parathyroid adenomas are reported to be ectopic. The majority of ectopic anterior mediastinal adenomas are found within the thymus or closely related to it. During embryological development, the inferior parathyroid glands and the thymus originate from the third pharyngeal pouch and migrate down together.

This case shows that accurate preoperative localisation of ectopic parathyroid adenomas through two different diagnostic modalities leads to efficient and successful surgical treatment of hyperparathyroidism.